1. Technical Field
The present invention relates to a liquid ejecting apparatus and a method of controlling the same.
2. Related Art
According to an ink jet printer, which is one example of a liquid ejecting apparatus, in a state where a power source is turned off, or in a standby state where recording is not performed when the power source is turned on, the nozzle surface of a recording head is sealed (capped) by a capping member. Therefore, evaporation from the nozzles of the solvent from the ink is suppressed. However, since the nozzle surface is released from the capping state during printing operations (during recording operation), the meniscus of the nozzle is exposed to the atmosphere. For this reason, during a period in which the nozzle surface is opened from the capping member, since the solvent of ink gradually evaporates from the nozzle with the passage of time, the viscosity of ink in the vicinity of the nozzle is increased. In addition, when capped, even though the nozzle forming surface of the recording head is sealed by the capping member or the like, a space is formed between the capping member and the nozzle surface. As the meniscus of ink is exposed to the air remaining in the space, it is hard to completely suppress the solvent of ink from naturally evaporating. If the increased viscosity of ink becomes significant, a problem (ejection fault) is likely to happen, for example, the weight or flight velocity of ink to be ejected is decreased, or the ink is not ejected. Since, in a short period of time, the viscosity of the ink in the vicinity of the meniscus is changed so that ink is difficult to be fluctuated using a pressure generating element, a problem is likely to happen, for example, the above-described ejection fault occurs or the flying direction of ink is curved so that its landing position is deviated from.
In order to prevent the ejection fault of ink as described above, various maintenance processes are executed. For example, the pressure generating element is driven to vary the pressure in a pressure chamber, so that liquid droplets are idle-ejected (hereinafter referred to as flushing) from the nozzles to forcibly remove ink with increased viscosity or bubbles contained in ink. In order to more reliably discharge ink with increased viscosity or the bubbles existing in an ink passage (liquid passage) together with ink from the nozzles by the flushing, it is necessary to apply as high as possible a pressure fluctuation to ink or bubbles. Accordingly, for example, as disclosed in JP-A-2009-73074, a printer which can produce a driving pulse for the flushing (the maintenance) has been proposed, in which the pressure variation applied to the inside of the pressure chamber by the pressure generating element is sympathetically with the natural characteristic of the liquid generated in the pressure chamber to make the pressure fluctuation applied to the inside of the pressure chamber large.
However, in the case of using the driving pulse for the flushing, as the pressure fluctuation of ink in the pressure chamber is increased, residual vibration resulting from the same is also increased. For this reason, in the state where the meniscus in the nozzle is disordered and thus the meniscus is unstable, if a next driving pulse is applied to the pressure generating element, the flying of ink ejected from the nozzle is curved, so that the flown ink is not likely to land at a predetermined position. In the case where the flushing operation is transited to the recording operation in a state where the meniscus is unstable, the ejection fault likely occurs at the time of a recording operation to cause the image quality, such as a recording image, to deteriorate. In addition, there is a problem in that, after ink, of which the viscosity increase is particularly advanced, in the vicinity of the meniscus at the time of flushing is ejected, when the driving pulse for the flushing is repeatedly applied to the pressure generating element and thus is continuously used, it is difficult to suppress the amount of ink to be consumed.